What is base number, and what are we measuring?

Base Number measures an engine oil’s ability to neutralize acids and prevent corrosion as the oil ages.  This is why you’ll often hear the term “reserve alkalinity” regarding Base Number. Base Number changes are measured from new or fresh oil levels and drops over time as it becomes more acidic. Tracking Base Number allows you to monitor the useful life of the oil and determine when to change the oil. Generally, you want to start to consider condemning your lubricant when the value of your Base Number drops by half (i.e your fresh oil baseline is 4 and your used value is 2). A low base number indicates your oil’s ability to counteract acids has diminished.

Acids form naturally as engine oil ages from the by-products of oxidation, thermal stress, and the combustion process. As the oil becomes more acidic this can increase wear and affect your oils performance. Oil manufacturers take this into consideration and supplement their base engine oils with additives to help combat acid build up. To be able to effectively utilize the Base Number test there needs to be a detergent package in the oil, as some oils do not have a detergent package.

Benefits of testing base number

With respect to mobile fleets, monitoring Base Number is especially critical. You want to be aware of  when your oil is about to lose the ability to combat these acids and increase the risk of additional wear and potential failures.

There are three primary benefits of testing Base Number routinely: prevention of corrosion and contamination, optimized oil drain intervals, and increased fuel efficiency.

Preventing corrosion, reducing wear, and contamination

As your engine runs and the combustion process happens, acids will accumulate, and your base number will drop as your additive package works to neutralize those acids. As these acids build up you can get harmful sludge deposits in your engine further accelerating the wear rate of your components. Other contaminants such as water and fuel can also impact on an oil’s detergency package and reduce its ability to interact with acids in the oil.  You can proactively monitor these parameters by doing routine oil analysis and ensuring Base Number is being reported and trended over time from a new oil baseline.  

Optimizing oil drain intervals

With supply chain issues, labor costs, and environmental factors being hot topics in recent years, oil drain optimizations are more important than ever before.  If you are trying to optimize your oil drain intervals measuring your Base Number is a critical marker. It is imperative you have a new oil baseline value for your oil when doing these types of trials for trending. If you are looking to perform an extended drain interval trial,  you may want to increase your sample frequency during trial period and monitor Base Number closely for the half-baseline point. However, if you are noticing your Base Number drops quickly, try and tighten those intervals to before your Base Number reaches half it’s baseline value.

Increased fuel efficiency

Monitoring your Base Number leads to optimal oil condition and can contribute to an overall increase engine efficiency. As your engine runs more efficiently this will in turn reduce fuel consumption and thus decreasing your cost of fuel. The less fuel that you are burning due to having increased fuel efficiency, the less emissions your fleet will produce. This will create an overall more environmentally conscious fleet.

Learn More

Adding Base Number to your mobile fleets, whether it be mining equipment, construction vehicles, buses, or trucks, gives you an important metric to know so you get the best value from your oil, but also the best mileage from your engines and your fuel. Fluid Life offers Base Number as part of the MOB4 and TRANS3 Lubricant and Component Life Extension oil analysis packages or as an individual test which can be purchased à la carte (three test methods available: ASTM D2896 mod. / ASTM D4739 mod. / FL Method).

Contact us today to learn about adding Base Number to your program or implementing an extended drain trial.